Means for preventing or limiting interchange of liquids between communicating vessels



June 1, 1965 v. lVANOFF 3,135,345

MEANS FOR PREVENTING 0R LIMITING INTERCHANGE OF LIQUIDS BETWEENCOMMUNICATING vEssELs Filed April 25, 1963 United States Patent 3 186345 MEANS FOR PREVENTING 0R LIMITING INTER- CHANGE OF LIQUIDS BETWEENCOMMUNI- CATING VESSELS Victor Ivanoif, Harpenden, England, assignor toHayward- This invention relates to submersible electric motor and pumpunits of the type, hereinafter referred to as the type defined, in whichthe motor and pump are enclosed in a casing forming an upper, motorchamber, and a lower, pump chamber, the two chambers being joined by arelatively narrow neck portion through which extends, with clearance, ashaft carrying the motor rotor at its upper end, and the pump rotor atits lower end, the liquid in the pump chamber having access to the motorchamber by Way of the annular clearance gap between the shaft and theneck of the casing.

When a unit of the type defined is used for pumping liquids at hightemperature, the pump chamber is filled with hot liquid which tends tobe carried by convection currents through the annular gap up to themotor chamber. Apart from the danger of over heating of the motor whichis involved, the heat losses can, in large installations, amount to tensof horsepower. To prevent over heating of the motor it is known toprovide an external coiling system, hot liquid being tapped off from thelower end of the motor chamber, cooled, and passed back to the casing atthe upper end of the motor chamber. The circulation of liquid throughthe external cooling system is forced by an auxiliary impeller carriedat the upper end of the motor shaft. The unit may, however, be requiredfor hot stand-by duty, that is to say it may be immersed in the liquid,so that the liquid fills the casing, in readiness for immediate use inthe event of the failure of another pump. In these circumstances themotor shaft is stationary and so the auxiliary impeller is not operativeto provide a forced circulation of liquid through the external coolingsystem, and the liquid in the motor chamber tends to become heated byconvection.

The present invention provides means for limiting the interchange byconvection of the relatively hot liquid in the lower, pump chamber andthe relatively cool liquid in the upper, motor chamber.

In accordance with the present invention there is provided a submersibleelectric motor pump unit of the type herein defined, in which there isprovided, at one end of the annular passage, a liquid trap or labyrinthincluding a downwardly directed wall surrounding the mouth of thepassage, the arrangement being such that in order to pass from the lowerchamber to the upper chamber through the annular passage, liquid mustpass downwardly below the lower edge of the said wall.

One form of submersible electric motor pump unit in accordance with theinvention will now be described, with reference to the accompanyingdrawing, which is an elevation, partly in axial section, of the unit.

The electric motor pump unit shown in the drawing comprises a casing inthree parts, an upper portion 1 defining a motor chamber, a lowerportion 2 defining a pump chamber and a relatively narrow neck portion 3connecting the upper and lower portions. A shaft 4, common to the motorand the pump, carries the motor rotor at its upper end, for co-operationwith stator windings mounted within the upper casing portion 1. Theshaft extends with clearance through the neck portion 3, so that anannular passage 5 is defined between the shaft and the neck, and at itslower end, within the pump chamber,

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the shaft carries a pump impeller 6. The pump chamber is provided withthe usual inlet 7 and outlet 8.

Just beyond the upper end of the annular passage 5, there is secured tothe shaft 4, in sealed relation therewith, a labyrinth comprising agenerally bell shaped member 11 concentric with and surrounding theshaft, with its mouth facing the adjacent upper end of the passage 5. Atubular baflle 12 is mounted at the upper end of the annular passage 5so as to form an upward extension thereof, and extends into the bellalthough spaced therefrom, with its upper edge at a higher level thanthe lower edge of the bell.

With this arrangement, hot liquid rising through the neck of the casingpasses into a trapped space within the bell 11, and to escape from thisspace must first pass downwardly below the lower edge of the bell,through the cooler liquid surrounding the bell and the bafile 12.

This trap or labyrinth arrangement can be inverted by providing a secondlabyrinth comprising an inverted bell 13 on the shaft 4 adjacent thelower end of the passage 5, and a downwardly extending tubular baffle 14at the lower end of the passage. For hot liquid to pass from the pumpchamber to the annular passage, it must pass below the lower edge of thebaffle, through the relatively cool liquid trapped within the bell.

In order to inhibit heat transference by conduction through the bells11, 13, the tubular baffles 12, 14 and the shaft, all of which are ofmetal, layers 11A, 13A, 12A and 14A, of heat insulating material, suchas impregnated asbestos, are provided on appropriate surfaces of thebells and the bafiles, respectively. The layers are held in place bylayers of metal cladding 11B, 13B, 12B

and 14B, respectively.

It will be apparent to those skilled in the art that the liquid traparrangements described above can be provided at either the lower end orthe upper end of the annular passage 5, but they are preferably providedat both ends, as described and illustrated.

What is claimed is:

1. A submersible electric motor and pump assemblage for pumping liquid,said assemblage comprising a housing .including a pump chamber, a motorchamber and a tubular neck portion joining the pump chamber and themotor chamber, a rotary pump within the pump chamber and an electricmotor within the motor chamber, said motor having a drive shaftextending through said neck portion -with clearance to define an annularpassage connecting the two chambers and coupled to the pump for rotatingthe same, said pump chamber having an inlet and an outlet for liquid tobe pumped, the liquid flooding both chambers and the annular passage inthe submersed condition of the assemblage, and a labyrinth meansadjacent to one end of said annular passage, said labyrinth meansinhibiting an upward flow of convection currents from the pump chambertowards the motor chamber by constraining said current to flow along atortuous path exposing the same to a cooling action by liquid in themotor chamber prior to entering said motor chamber.

2. A submersible electric motor and pump assemblage for pumping liquid,said assemblage comprising a housing including a pump chamber, a motorchamber and a tubular neck portion joining the pump chamber and themotor chamber, a rotary pump within the pump chamber and an electricmotor within the motor chamber, said motor having a drive shaftextending through said neck portion with clearance to define an annularpassage connecting the two chambers and coupled to the pump for rotatingthe same, said pump chamber having an inlet and an outlet for liquid tobe pumped, the liquid flooding both chambers and the annular passage inthe submersed condition of the assemblage, and a labyrinth meansadjacent to one end of said annular passage, said labyrinth meansincluding a bell-shaped member disposed in the motor chamber adjacent tothe respective end of the annular passage in lengthwise alignmenttherewith, said bell-shaped member being surrounded by' and filled withliquid in the motor chamber, the open side of the bell-shaped memberfacing towards said passage to inhibit an upward flow of convectioncurrents by guiding said currents through said passage at least partlyinto the bell-shaped member and then around the free rim thereof,thereby exposing convection currents flowing from the pump chambertowards the motor chamber to a cooling action by the liquid in the motorchamber prior to entering said motor chamber.

3. A submersible electric motor and pump assemblage for pumping liquid,said assemblage comprising a housing including a pump chamber, a motorchamber and a tubular neck portion joining the pump chamber and themotor chamber, a rotary pump within the pump chamber and an electricmotor within the motor chamber, said motor having a drive shaftextending through said neck portion with clearance to define an annularpassage connecting the two chambers and coupled to the pump for rotatingthe same, said pump chamber having an inlet and an outlet for liquid tobe pumped, the liquid flooding both chambers and the annular passage inthe submersed condition of the assemblage, and a labyrinth meansadjacent to one end of said annular passage, said labyrinth meansincluding a bell-shaped member disposed in the motor chamber coaxialwith the said shaft sealed thereto, the open side of said bell-shapedmember facing toward said annular passage, said bell-shaped member beingsurrounded by and filled with liquid in the motor chamber, and a tubularbafi'le forming an extension of said annular passage within the motorchamber and extending into the open side of the bell-shaped memberspaced from the side and bottom walls thereof to form a tortuous pathinhibiting an upward flow of convection currents emerging from said oneend of the annular passage by exposing such currents to a cooling actionby liquid in the motor chamber prior to entering the same.

4. An assemblage according to claim 2 wherein wall surfaces of saidbell-shaped member are lined with a heatinsulating material to inhibitheat transfer by conduction through said lined wall surfaces.

5. A submersible electric motor and pump assemblage for pumping liquid,said assemblage comprising a housing including a pump chamber, a motorchamber and a tubular neck portion joining the pump chamber and themotor chamber, a rotary pump within the pump chamber and an electricmotor within the motor chamber, said motor having a drive shaftextending through said neck portion with clearance to define an annularpassage connecting 4 the two chambers and coupled to the pump forrotating the same, said pump chamber having an inlet and an outlet forliquid to be pumped, the liquid flooding both chambers and the annularpassage in the submersed condition of the assemblage, and a labyrinthmeans in each chamber adjacent to the respective end of said annularpassage, each of said labyrinth means inhibiting an upward flow ofconvection currents from one chamber to the other through said passageby constraining said currents to flow along a tortuous path prior toentering and leaving the respective chamber.

6. A submersible electric motor and pump assemblage for pumping liquid,said assemblage comprising a housing including a pump chamber, a motorchamber and a tubular neck portion joining the pump chamber and themotor chamber, a rotary pump within the pumpchamber and an electricmotor within the motor chamber, said motor having a drive shaftextending through said neck portion with clearance to define an annularpassage connecting the two chambers and coupled to the pump for rotatingthe same, said pump chamber having an inlet and an outlet for liquid tobe pumped, the liquid flooding both chambers and the annular passage inthe submersed condition of the assemblage, and a labyrinth means in eachchamber adjacent to the respective end of said annular passage, each ofsaid labyrinth means including a bellshaped member disposed in therespective chamber coaxial with said shaft sealed thereto, the open sideof each of said bell-shaped members facing toward said annular passage,each of said bell-shaped members being surrounded by and filled withliquid in therespective chamber, and a tubular bafile forming anextension of said annular passage within the respective chamber andextending into the open side of the respective bell-shaped member spacedfrom the side and bottom walls thereof to form a tortuous path adjacentto each end of the annular passage inhibiting an upward flow ofconvection currents from one chamber to the other through said passageby constraining said currents to flow along said tortuous path prior toentering and leaving the respective chamber.

References (Iited by the Examiner UNITED STATES PATENTS 1,346,924 7/20VVilfley 103-411 2,381,823 8/45 La Bour 163-111 2,677,328 5/54 Vitek103l1l LAURENCE V. EFNER, Primary Examiner.

ROBERT M. WALKER; Examiner.

1. A SUBMERSIBLE ELECTRIC MOTOR AND PUMP ASSEMBLAGE FOR PUMPING LIQUID, SAID ASSEMBLAGE COMPRISING A HOUSING INCLUDING A PUMP CHAMBER, A MOTOR CHAMBER AND A TUBULAR NECK PORTION JOINING THE PUMP CHAMBER AND THE MOTOR CHAMBER, A ROTARY PUMP WITHIN THE PUMP CHAMBER AND AN ELECTRIC MOTOR WITHIN THE MOTOR CHAMBER, SAID MOTOR HAVING A DRIVE SHAFT EXTENDING THROUGH SAID NECK PORTION WITH CLEARANCE TO DEFINE AN ANNULAR PASSAGE CONNECTING THE TWO CHAMBERS AND COUPLED TO THE PUMP FOR ROTATING THE SAME, SAID PUMP CHAMBER HAVING AN INLET AND AN OUTLET FOR LIQUID TO BE PUMPED, THE LIQUID FLOODING BOTH CHAMBERS AND THE ANNULAR PASSAGE IN THE SUBMERSED CONDITION OF THE ASSEMBLAGE, AND A LABYRINTH MEANS ADJACENT TO ONE END OF SAID ANNULAR PASSAGE, SAID LABYRINTH MEANS INHIBITING AN UPWARD FLOW OF CONVECTION CURRENTS FROM THE PUMP CHAMBER TOWARDS THE MOTOR CHAMBER BY CONSTRAINING SAID CURRENT TO FLOW ALONG A TORTUOUS PATH EXPOSING THE SAME TO A COOLING ACTION BY LIQUID IN THE MOTOR CHAMBER PRIOR TO ENTERING SAID MOTOR CHAMBER. 